overview of OpenGL
rendering details
rendering details
This section provides the details for several of HP’s rendering capabilities. These rendering capabilities range from the way HP implements its default visuals to the way HP deals with the decomposition of concave quadrilaterals.
default visuals
Instead of placing the default visual in the deepest image buffer, HP puts the default visual in the overlay planes. This behavior can be modified using SAM to adjust the
EXP and EXP2 fogging
The Virtual Memory Driver’s implementation of fog applies fog per fragment. Hardware devices implement EXP and EXP2 fog per fragment and linear fog per vertex.
bow-tie quadrilaterals
A quadrilateral has four vertices that are coplanar. When this quadrilateral is twisted and you look at a front view of it on the display, there appears to be a fifth vertex. This fifth vertex which is not a true vertex will have no attributes, therefore, the color at what appears to be the intersection of two lines will in most cases be different from what is expected. HP treats the two parts of the bow tie as two separate triangles that have attributes assigned to their vertices. This special rendering process takes care of the color problem at the
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